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Kinetics: OCR A‑Level Chemistry B questions

Every OCR A-Level Chemistry B exam question on CI Kinetics (specification points CI(a)–(e)), 2016–2025, with its mark scheme and examiner’s report.

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2,049 questions

  1. Q23

    June 2025 · Paper 1

    1 markCI Kinetics
    The whole paper ↗
    June 2025 Paper 1, question 23: A scientist studies the reaction: J K 1 After 24 minutes there is 8 th as much J left as at the start. What is the half-life of the reaction in minutes? A 4 B 6

  2. Q35(a)(iii)

    June 2025 · Paper 1

    3 marksCI Kinetics
    The whole paper ↗
    June 2025 Paper 1, question 35(a)(iii): A chemist measures the rate constant for this reaction at two temperatures. The chemist’s results are shown in the table. T / K ln k Temperature 1 313 4.777 Tem

  3. Q3(a)

    June 2025 · Paper 2

    1 markCI Kinetics
    The whole paper ↗
    June 2025 Paper 2, question 3(a): Explain why a large excess of Cl 2 is required. [1]

  4. Q3(b)

    June 2025 · Paper 2

    2 marksCI Kinetics
    The whole paper ↗
    June 2025 Paper 2, question 3(b): Use the graph to work out the initial rate of the reaction in mol dm–3 s–1. Show your working on the graph. Initial rate = mol dm–3 s–1 [2]

  5. Q3(c)(i)

    June 2025 · Paper 2

    1 markCI Kinetics
    The whole paper ↗
    June 2025 Paper 2, question 3(c)(i): What can the scientists conclude from this? [1]

  6. Q3(c)(ii)

    June 2025 · Paper 2

    1 markCI Kinetics
    The whole paper ↗
    June 2025 Paper 2, question 3(c)(ii): Fill in the missing value in Table 3.1. [1]

  7. Q3(c)(iii)

    June 2025 · Paper 2

    4 marksCI Kinetics
    The whole paper ↗
    June 2025 Paper 2, question 3(c)(iii): Plot a graph of initial rate against [NO]2. Use the data in Table 3.1. Include the origin. Draw the line of best fit. [4]

  8. Q3(c)(iv)

    June 2025 · Paper 2

    1 markCI Kinetics
    The whole paper ↗
    June 2025 Paper 2, question 3(c)(iv): Explain why the graph shows that the reaction is second order with respect to NO. [1]

  9. Q3(d)(i)

    June 2025 · Paper 2

    1 markCI Kinetics
    The whole paper ↗
    June 2025 Paper 2, question 3(d)(i): Complete the rate equation for the reaction. Rate = k × [1]

  10. Q3(d)(ii)

    June 2025 · Paper 2

    1 markCI Kinetics
    The whole paper ↗
    June 2025 Paper 2, question 3(d)(ii): Give the units of the rate constant, k. [1]

  11. Q3(d)(iii)

    June 2025 · Paper 2

    1 markCI Kinetics
    The whole paper ↗
    June 2025 Paper 2, question 3(d)(iii): Explain why the value of the rate constant cannot be calculated from data in this question. [1]

  12. Q3(d)(iv)

    June 2025 · Paper 2

    3 marksCI Kinetics
    The whole paper ↗
    June 2025 Paper 2, question 3(d)(iv): The scientists conclude that a possible mechanism is as shown below, with step 2 being rate-determining. NO + Cl 2 NOCl 2 Step 1 NOCl 2 + NO 2NOCl Step 2 Give t

  13. Q32(a)(i)

    June 2024 · Paper 1

    3 marksCI Kinetics
    The whole paper ↗
    June 2024 Paper 1, question 32(a)(i): Use the results to show that the rate equation is: Rate = k[NO]2 [3]

  14. Q32(a)(ii)

    June 2024 · Paper 1

    2 marksCI Kinetics
    The whole paper ↗
    June 2024 Paper 1, question 32(a)(ii): Calculate the rate constant, k, for the reaction in Equation 32.1 and give its units. k = units [2]

  15. Q32(b)(i)

    June 2024 · Paper 1

    3 marksCI Kinetics
    The whole paper ↗
    June 2024 Paper 1, question 32(b)(i): The rate equation for this reaction is: Rate = k[NO2]2 A student says that this reaction takes place in a single step. Explain why this cannot be correct and gi

  16. Q32(b)(ii)

    June 2024 · Paper 1

    4 marksCI Kinetics
    The whole paper ↗
    June 2024 Paper 1, question 32(b)(ii): A chemist studies the reaction in Equation 32.2 and measures the rate constant, k, at different temperatures. The chemist plots ln k against 1/T on a graph as s

  17. Q22

    June 2023 · Paper 1

    1 markCI Kinetics
    The whole paper ↗
    June 2023 Paper 1, question 22: A student plots a graph of ln k (y-axis) against 1/T for a reaction. The student draws the straight line of best fit. The Arrhenius equation is ln k = –Ea/RT +

  18. Q4(a)(i)

    June 2023 · Paper 3

    2 marksCI Kinetics
    The whole paper ↗
    June 2023 Paper 3, question 4(a)(i): Explain why the results of Experiment 1 show that the rate of reaction does not vary with the iodine concentration. [2]

  19. Q4(a)(ii)

    June 2023 · Paper 3

    1 markCI Kinetics
    The whole paper ↗
    June 2023 Paper 3, question 4(a)(ii): During Experiment 1, the students ensured the concentration of propanone remained virtually constant. How did they do this? [1]

  20. Q4(b)

    June 2023 · Paper 3

    1 markCI Kinetics
    The whole paper ↗
    June 2023 Paper 3, question 4(b): Suggest why the total volume is kept constant in Experiment 2. [1]
All 61 questions on Kinetics, as a list
  1. June 2025, Paper 1, Q23 (1 mark): A scientist studies the reaction: J K 1 After 24 minutes there is 8 th as much J left as at the start. What is the half-life of the reaction in minutes? A 4 B 6
  2. June 2025, Paper 1, Q35(a)(iii) (3 marks): A chemist measures the rate constant for this reaction at two temperatures. The chemist’s results are shown in the table. T / K ln k Temperature 1 313 4.777 Tem
  3. June 2025, Paper 2, Q3(a) (1 mark): Explain why a large excess of Cl 2 is required. [1]
  4. June 2025, Paper 2, Q3(b) (2 marks): Use the graph to work out the initial rate of the reaction in mol dm–3 s–1. Show your working on the graph. Initial rate = mol dm–3 s–1 [2]
  5. June 2025, Paper 2, Q3(c)(i) (1 mark): What can the scientists conclude from this? [1]
  6. June 2025, Paper 2, Q3(c)(ii) (1 mark): Fill in the missing value in Table 3.1. [1]
  7. June 2025, Paper 2, Q3(c)(iii) (4 marks): Plot a graph of initial rate against [NO]2. Use the data in Table 3.1. Include the origin. Draw the line of best fit. [4]
  8. June 2025, Paper 2, Q3(c)(iv) (1 mark): Explain why the graph shows that the reaction is second order with respect to NO. [1]
  9. June 2025, Paper 2, Q3(d)(i) (1 mark): Complete the rate equation for the reaction. Rate = k × [1]
  10. June 2025, Paper 2, Q3(d)(ii) (1 mark): Give the units of the rate constant, k. [1]
  11. June 2025, Paper 2, Q3(d)(iii) (1 mark): Explain why the value of the rate constant cannot be calculated from data in this question. [1]
  12. June 2025, Paper 2, Q3(d)(iv) (3 marks): The scientists conclude that a possible mechanism is as shown below, with step 2 being rate-determining. NO + Cl 2 NOCl 2 Step 1 NOCl 2 + NO 2NOCl Step 2 Give t
  13. June 2024, Paper 1, Q32(a)(i) (3 marks): Use the results to show that the rate equation is: Rate = k[NO]2 [3]
  14. June 2024, Paper 1, Q32(a)(ii) (2 marks): Calculate the rate constant, k, for the reaction in Equation 32.1 and give its units. k = units [2]
  15. June 2024, Paper 1, Q32(b)(i) (3 marks): The rate equation for this reaction is: Rate = k[NO2]2 A student says that this reaction takes place in a single step. Explain why this cannot be correct and gi
  16. June 2024, Paper 1, Q32(b)(ii) (4 marks): A chemist studies the reaction in Equation 32.2 and measures the rate constant, k, at different temperatures. The chemist plots ln k against 1/T on a graph as s
  17. June 2023, Paper 1, Q22 (1 mark): A student plots a graph of ln k (y-axis) against 1/T for a reaction. The student draws the straight line of best fit. The Arrhenius equation is ln k = –Ea/RT +
  18. June 2023, Paper 3, Q4(a)(i) (2 marks): Explain why the results of Experiment 1 show that the rate of reaction does not vary with the iodine concentration. [2]
  19. June 2023, Paper 3, Q4(a)(ii) (1 mark): During Experiment 1, the students ensured the concentration of propanone remained virtually constant. How did they do this? [1]
  20. June 2023, Paper 3, Q4(b) (1 mark): Suggest why the total volume is kept constant in Experiment 2. [1]
  21. June 2023, Paper 3, Q4(c)(i) (1 mark): An extended version of Table 4.1 from the Insert is given below. Use the data in this table to calculate the rates of reaction (in cm3 of iodine solution decolo
  22. June 2023, Paper 3, Q4(c)(ii) (3 marks): The students do a text book search and find that the rate equation for the reaction is: Rate = k [propanone][H+] Explain whether the results of Experiment 1 and
  23. June 2023, Paper 3, Q4(d)(i) (1 mark): Show why the rate of reaction of iodine in Run A is 1.1 × 10–5 mol dm–3 s–1. [1]
  24. June 2023, Paper 3, Q4(d)(ii) (4 marks): Using the data in Table 4.1 for Experiment 2 Run A, calculate the initial concentrations of hydrochloric acid and propanone in the flask. Use these values, alon
  25. June 2023, Paper 3, Q4(e) (4 marks): A student proposes the reaction mechanism below for the iodination of propanone. O OH Step 1 H+ + + C C H3C CH3 H3C CH3 OH OH Step 2 + H+ + C C H3C CH3 H2C CH3
  26. June 2023, Paper 3, Q4(f) (1 mark): The students wear safety goggles and protective gloves when carrying out the experiments. Using the information from the insert, suggest one other necessary hea
  27. June 2022, Paper 2, Q3(a)(i) (3 marks): Use the graph to measure two half-lives to show that the kinetics are first order. Show your working on the graph. first half-life = second half-life = [3]
  28. June 2022, Paper 2, Q3(a)(ii) (1 mark): Use the graph to measure the initial rate of the reaction in mol dm–3 s–1. initial rate = mol dm–3 s–1 [1]
  29. June 2022, Paper 2, Q3(a)(iii) (2 marks): The graph shows that the reaction in equation 3.1 is first order with respect to hydrogen peroxide. Explain why the orders with respect to the other reagents ca
  30. June 2022, Paper 2, Q3(b)(i) (2 marks): Suggest why the tubes go dark blue after a period of time rather than gradually from the start. [2]
  31. June 2022, Paper 2, Q3(b)(ii) (1 mark): How can the relative rates of reaction be found from the students’ results? [1] 10 2H+ + H2O2 + 2I– I2 + 2H2O Equation 3.1
  32. June 2022, Paper 2, Q3(c) (6 marks): Some students read about the reaction between hydrogen peroxide and iodide ions as shown in equation 3.1. 2H+ + H2O2 + 2I– I2 + 2H2O Equation 3.1 (c)* The stude
  33. June 2022, Paper 2, Q3(d) (4 marks): The students find data for the variation of the rate constant, k, with temperature. From their data they plot the graph below. 1 / T / K–1 0 0.0028 0.0029 0.003
  34. November 2021, Paper 1, Q21 (1 mark): The decomposition of hydrogen peroxide is first order with respect to hydrogen peroxide. The half-life for the decomposition is 900 seconds. What percentage of
  35. November 2021, Paper 1, Q23 (1 mark): A student determines the rate constant for a reaction at various temperatures and plots ln k against 1 / T. A straight line is produced. The Arrhenius equation
  36. November 2021, Paper 1, Q35(a)(i) (1 mark): The scientists conclude that the reaction is not first order with respect to N2O. Suggest why they conclude this. [1]
  37. November 2021, Paper 1, Q35(a)(ii) (3 marks): Plot a graph of rate against the square of concentration on the grid on page 29. [3]
  38. November 2021, Paper 1, Q35(a)(iii) (1 mark): Use your graph to complete the rate equation for the reaction. Rate = k × [1]
  39. November 2021, Paper 1, Q35(a)(iv) (3 marks): Use your graph to find a value for the rate constant, k, and give its units. rate constant = units [3]
  40. November 2021, Paper 1, Q35(b)(i) (2 marks): Use the shape of the graph to give the order of the catalysed reaction with respect to N2O. Explain how you arrived at your answer. [2]
  41. November 2020, Paper 1, Q21 (1 mark): A student plots ln k (y-axis) against 1 / T (in K−1) for a reaction. The student gets a straight line graph that corresponds to the Arrhenius equation: ln k = −
  42. November 2020, Paper 3, Q4(a) (6 marks): This question refers to the Practical Insert that is found inside this document. (a)* Method 1 uses a series of titrations to determine the concentration of hyd
  43. November 2020, Paper 3, Q4(b)(i) (2 marks): Using the data from Table 4.1 in the Practical Insert, plot a graph on the grid below. Include a curve of best fit. 60 50 40 [OH–] ×10–3 / mol dm–3 30 20 10 0 0
  44. November 2020, Paper 3, Q4(b)(ii) (2 marks): Use your graph to calculate the time taken for the concentration of hydroxide ions to fall from 40 × 10−3 to 20 × 10−3 and from 20 × 10−3 to 10 × 10−3 mol dm−3.
  45. November 2020, Paper 3, Q4(b)(iii) (2 marks): Explain how the graph shows that the overall order of the reaction is first order. [2]
  46. November 2020, Paper 3, Q4(b)(iv) (2 marks): A student is told that the reaction followed using Method 1 goes by mechanism B. The student says that the first reaction in mechanism B must be the rate-determ
  47. November 2020, Paper 3, Q4(c)(i) (2 marks): Use the data in Table 4.2 to determine the order of reaction with respect to 1-bromobutane and hydroxide ions in Method 2. Give your reasoning. [2]
  48. November 2020, Paper 3, Q4(c)(ii) (1 mark): Complete the rate equation for the reaction in part (c)(i). Rate = [1]
  49. June 2019, Paper 2, Q4(b)(i) (4 marks): Use the data in the table to plot a graph to determine the half-life for the reaction. Label the axes. half-life = s [4]
  50. June 2019, Paper 2, Q4(b)(ii) (1 mark): How does the graph show that the reaction in equation 4.1 is first order with respect to N2O5? Draw construction lines on the graph to explain your answer. [1]
  51. June 2019, Paper 2, Q4(c) (2 marks): The gradient of the graph at 1000 s is 9.8 × 10−5 mol dm−3 s−1. Work out the rate constant for the reaction in equation 4.1 at 315 K. Give the units in your ans
  52. June 2019, Paper 2, Q4(d) (3 marks): The reaction in equation 4.1 was repeated with a fixed concentration of N2O5 at different temperatures. A graph of l n k against 1 T for the reaction in equatio
  53. June 2019, Paper 2, Q4(e) (3 marks): A student suggests the following mechanism for the reaction in equation 4.1. The reaction is first order with respect to N2O5. N2O5 → NO2 + NO3 step 1 NO3 → O2
  54. June 2018, Paper 1, Q16 (1 mark): Which statement about the rate determining step of a reaction is correct? A It is the fast step. B It cannot involve a catalyst. C It does not involve zero orde
  55. June 2018, Paper 1, Q24 (1 mark): Which statement about the Arrhenius equation is correct? A A plot of ln k against T gives a straight line. B When T is very large ln k almost equals ln A. C Ea
  56. June 2018, Paper 2, Q3(e)(i) (2 marks): Write the rate equation that would follow from the student’s statement. Give the units of the rate constant. Rate equation: Units of rate constant [2]
  57. June 2017, Paper 1, Q19 (1 mark): Nitrogen dioxide reacts with carbon monoxide as in the equation below. NO2 + CO NO + CO2 The mechanism is: NO2 + NO2 NO + NO3 Slow NO3 + CO NO2 + CO2 Fast Which
  58. June 2017, Paper 3, Q2(a)(i) (1 mark): Why was the length of the magnesium ribbon kept the same? [1]
  59. June 2017, Paper 3, Q2(b) (1 mark): The students predict that the reaction will be second order with respect to acid. Write the rate equation that would be appropriate for this prediction. [1]
  60. June 2017, Paper 3, Q2(c) (5 marks): The students plot a graph of volume of hydrogen against time. The graph of the results when the concentration of hydrochloric acid is 0.5 mol dm3 is shown below
  61. June 2017, Paper 3, Q2(d) (6 marks): The students decide to measure the activation enthalpy for the reaction. They repeat the experiment at different temperatures using a fixed concentration of aci

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